What are common ways to say “Thank you very, very much” in a formal or business setting? I am interested in both, phrases for a written letter, and formal ways to express "thank you" in talking. Are they different?
There is not the answer, but I think the most common and formal one would be
Vielen herzlichen Dank
To thank in a regular way, in Germany, you say
while in Austria you say
But you can use both phrases in both countries. For a more intense way to thank, you can say in both countries:
Vielen, vielen Dank
Ich danke vielmals!
Sadly, I dont know how they thank in Switzerland, but I am sure, you will be understood also, if you use the phrases above.
The "best way" depends on the context in which it is used. Without any further details I would say:
Vielen, vielen Dank.
If it should be a little more personal:
Vielen lieben Dank.
To emphasize the very, you could say
(Meinen) besten Dank.
To add a more personal touch, herzlichen instead of besten works fine, in both cases you express above-average gratitude.
I would go with
Vielen, vielen Dank
Ich danke Ihnen sehr
which expresses your special gratitude because you explicitly say that it is you who is thanking the other.
However... I'm not sure that it is at all common to thank people a lot in business relations in Germany. It would be a weird bit too personal for my taste to express deep feelings of gratitude, especially if you say the circumstances are rather formal. You would rather emphasize how happy you are about the great opportunities you gain by this deal, or how much this decision has helped you to reach your goals.
Supplementary answer: For business settings I would suggest a longer sentence, like
Ich möchte mich bei Ihnen herzlichst bedanken.
Ich möchte mich bei Ihnen für Ihr/e/n
random positive attributesehr herzlich bedanken.
Usually, Germans tend to express emotions in not too many words, so a simple
would be the most common way to say that. And that is perfectly fine to do so, there is no need to do it more bloomy.
I saw the difference when having a friend from the U.S. visiting me here and I just proposed to do a little show-around, and she used words like
thank you sooo very much - if a German had uttered such words, I'd think he's kidding me, but with an American that means just
Nevertheless, Germans also had great poets and the language is able to express it in a more complex way, such as
Ich möchte Ihnen meinen allergrößten Dank zum Ausdruck bringen!
But one wouldn't use it in normal business talk, even in a formal one.
Ich danke Ihnen
are the best ways so far